Two groups of plant growth regulators (PGRs), seaweed extract and triazole chemical, have been used in turfgrass management for improving turf quality and strengthening turfgrass tolerance to environmental stress. In order to understand the

physiological functions and stress-tolerance mechanisms of the PGRs on turfgrass, a series of studies were conducted with perennial ryegrass (Lolium perenne L.). Ryegrass was treated with or without propiconazole (PPC) (1-( (2-(2,4-

dichlorophenyl)-4-propyl-l,3-dioxolan-2yl)methyl) IH-l,2,4-triazole) and a proprietary fortified seaweed extract (FSE), which were combined with or without drought and salinity stress treatment. Total lipids, fatty acid composition of polar lipids, and total free and conjugated sterols were determined by the thin layer chromatograph, gas chromatograph, and scanner densitometer. This study indicates that ppe and FSE affected the unsaturation of polar lipid fatty acids and concentration of free sterols, which are major factors in changing cell membrane fluidity and permeability. The PGR-induced-process to protect plant membrane function under drought and salinity stresses.